ABSTRACT Age-related macular degeneration (AMD) is a common, complex disease that results in loss of central vision. Both genetic and environmental factors contribute to AMD risk, and both operate over advancing age. In advanced AMD (due to either neovascularization or atrophy), loss of photoreceptor cells, retinal pigment epithelium (RPE), and choriocapillaris endothelial cells are all observed. Data from a variety of sources have revealed that eyes with early AMD are characterized by loss of choriocapillaris endothelial cells and increased activation of the membrane attack complex (MAC) of complement. The abundance of MAC increases by approximately 2-fold during normal aging, and in eyes with dry AMD, there is an additional ~ 2-fold increase of MAC compared to normal aging. Moreover, studies in cultured endothelial cells shows that choroidal cells are susceptible to MAC mediated lysis, and that this damage can be ameliorated pharmacologically. A better understanding of the molecular basis for MAC-mediated injury and MAC resistance in choroidal endothelial cells offers potential avenues for both a better understanding of the disease process as well as suggesting avenues to intervene in early AMD and, perhaps, prevent progression to end stage disease. Cells defend themselves from bystander complement injury by both fluid phase and cell surface inhibitors, but it is likely that other mechanisms that are also controlled by genes are involved in complement defense, including genes involved in regulating dynamic events at the plasma membrane. We propose to investigate the pathophysiology of choroidal endothelial cell death due to complement injury in AMD by screening a small guide RNA library and the CRISPR-Cas9 system to identify genes with a regulatory role in affecting choroidal endothelial cell death. Our experiments will lead to a better understanding of this blinding disease and may help to identify treatments that can be utilized for patients with AMD.